Conventional communications networks, for example particularly broadband communications networks, are a result of continuous evolution of technologies over a number of past decades. A conventional communications network comprises a plurality of network elements, such as switches, cross-connects, repeaters and terminals. Persons designing new communications networks, or modifications to existing communications networks have a large selection of hardware based equipment items available from different manufacturers, different equipment having different performances, and operating different transmission protocols according to different standards. Even the network equipment products available from a single manufacturer can vary considerably in functionality, capability and mode of operation due to the historical development of the products, and due to takeovers, mergers and alliances between different manufacturers within the telecommunications industry. There exists a large inventory of such available "legacy" equipment, both as products currently available from manufacturers, and as existing items of network equipment currently installed and in use in communications networks. On the other hand, there exists a considerable number of standards bodies and alliances of manufacturers, concerned with steering the evolution of new communications technologies and protocols with a view to standardization and interoperability of equipment from different manufacturers. Many of the current standards and evolving technologies will form the legacy equipment and systems of the future, thereby adding to the volume of "legacy" equipment in use.
Modern broadband communications networks are required to carry an increasing volume of communications data traffic, having a mixture of traffic characteristics driven by a variety of applications. Such applications include video on demand, voice communication, and computer to computer data transfer. Operators and users of networks need to be able to manage their network resources to make the most cost effective use of communications networks, and to provide adequate services to their customers. Management of a network is involves management of operations, administration, maintenance, and provisioning of network resources (OAMP). Briefly, these elements involve the following:
Operations involves the day-to-day and often minute-to-minute care and feeding of the communications network in order to ensure that it is fulfilling its designed purpose. Examples of operations include monitoring of the network by watching for faults and invoking corrective commands and/or maintenance actions to repair them, comparing measured network performance against objectives and taking corrective action and/or invoking maintenance. Taking corrective action involves operators issuing controls to correct a fault or performance problem or to resolve a customer complaint. PA1 Administration involves a set of activities involved with designing the network, processing orders, assigning addresses, tracking usage, and billing users of the network. PA1 Maintenance involves circumstances that arise when a network does not work as planned, or it is necessary to diagnose and repair system faults. PA1 Provisioning involves installing equipment, setting parameters, verifying that a service is operational and deinstallation of equipment or services. PA1 CMOT (Abbreviation of CMIP over TCP/IP) PA1 IIMC (abbreviation of ISO/CCITT Internet Management Coexistence) PA1 IBM (International Business Machines) have proposed how to organize a single management information base such that it can be independently accessed by either CMIP or SNMP protocols. PA1 The network management forum has specified a protocol independent management information base format and is encouraging the development of commercial tools to provide protocol specific access. PA1 The ATM Forum has used a protocol independent notation to model requirements for ATM network and element management. PA1 Each time a new network is designed, a new custom-made management information base needs to be created. PA1 Conventional methods of management information base creation involve considering the design of a management information base as a whole whenever a new type of network element is created, or whenever a new network element is added to an existing network. For example when a new network element is added to an existing network, changes to the data stored in the management information base must be added to reflect the addition of the new network element. In conventional management information bases, the changes to the management information base required on addition of a new network element are difficult to contain due to the cross-references between data items stored in the MIB. PA1 Conventional management systems are not easily scaleable. As the complexity of the network increases, so does the complexity of the management information base required. For networks having more than a few hundred nodes, a plurality of network management systems are used. This results in architectural complexity of management systems in order to compensate for lack of scaleability in the inherent design of the management system. PA1 a plurality of components, each component comprising a unit of manufacture providing a functionality within said network, and which is capable of being managed individually as a discrete entity; PA1 said plurality of components arranged into a plurality of assemblies of components, each said assembly arranged to co-operate with other said assemblies, and each said assembly capable of being managed as a whole; PA1 said method comprising the steps of:
Conventionally, such network management may be achieved through a network controller apparatus. As illustrated schematically in FIG. 1 herein, a conventional communications network comprises a plurality of heterogeneous network elements NE, controlled and operated by one or more network controllers NC. The network elements may be of different manufacturers', and having different capabilities and protocols. A network controller NC typically comprises a workstation capable of accessing an operation, administration and management (OAM) channel communicating with each of the network elements. The network controller receives and sends messages over the operation and management channel in the form of control signals in accordance with standard and/or proprietary protocols. Examples of widely used protocols include the simple network management protocol (SNMP) which is defined in EITF Standards. Another standard network management protocol is the known common management information protocol (CMIP) of the Open System Interconnect (OSI) Committee of the International Telecommunications Union (ITU-T). Other network management protocols in use include TL1 and a variety of proprietary management protocols. Currently, the two prevailing protocols used to convey management information in communications systems are SNMP and CMIP. There is general agreement that SNMP and its successor SNMP v2 are more suitable for customer premises equipment and private networks, whilst the common management information protocol, and the associated common management information service elements (CMISE) are more appropriate for carrier interconnection. For some devices, such as early asynchronous transfer mode (ATM) switches, it is simpler and easier to achieve interoperability with SNMP than it is with CMIP.
Although SNMP was developed with the intention of later intercepting the International Standard Organization Standards such as CMIP, there are fundamental differences between the SNMP and CMIP protocols which have traditionally inhibited inter-working of the two protocols. Differences between the SNMP and CMIP protocols are illustrated in table 1 herein.
TABLE 1 ______________________________________ CMIP (paradigm - object SNMP (paradigm - relational) oriented) Management Information Management Information ______________________________________ Complex object classes with Simple object types (simple attributes, events and actions variables without attributes, plus tables of simple variables) No actions or events (SNMP traps are not associated with objects Separate hierarchies for A single hierarchy which is registration (naming), used for both naming and containment and inheritance containment. No inheritance Identification of instances Identification of instances based on containment plus based on position in hierarchy distinguished attributes plus, for table entries, a simple index ______________________________________ value
Several attempts have been made to align the SNMP and CMIP protocols and models. However, many of these approaches are flawed. Such approaches include:
The internet community have proposed how to use the CMIP protocol to manage transmission and control protocol/internet protocol (TCP/IP). CMOT fails because it requires significant changes to internet equipment. CMOT has survived only as a definition of an alternative transport layer protocol for CMIP. PA2 The Network Management Forum (NMF) has endorsed a scheme for translation between CMIP and SNMP management information bases (MIBS). This approach is undesirable because it merely provides a syntactic translation between SNMP and CMIP MIB formats. PA2 representing an overall functionality of said network by an application model, in which each said function of said network is modeled independently of its implementation within said network; PA2 decomposing said application model into an implementation model, in which every function represented by said application model is represented in said implementation model; PA2 representing said application model as a first plurality of objects; PA2 representing said implementation model as a second plurality of objects; PA2 connecting said first plurality of objects with said second plurality of objects to obtain a combined object model; and PA2 constructing said management base in accordance with said combined object model.
In the Network Management Forum (NMF) approach, there is proposed a "Proxy" mechanism which translates between functionally equivalent service, protocol and management information base differences. SNMP object types are mapped to "equivalent" ISO/CCITT object classes and attributes as illustrated schematically in FIG. 2 herein. No attempt is made to modify the basic shape of the SNMP management information base, so classes normally seen in GDMO management information bases such as the connection object from ITU-T Recommendation G.803 do not appear. The structure of the management information base and the access mechanisms having protocol specific views of the management information base are cleanly separated in the NMF model. The NMF concept enables a network-wide model to be constructed which is independent of the various "views" upon it. Neither of the above approaches addresses the key issue of how to manage systems composed of multiple heterogeneous network elements.
Independent proposals made within the International Community for development of management models for communications networks include.
Referring to FIG. 3 herein in the IBM scheme, a protocol independent management information base 300 is provided with a generic interface 301. The generic interface 301 is accessed via an SNMP protocol object 302, and/or CMIP protocol object 303, comprising respectively an SNMP interface 304 and a CMIP interface 305.
However, despite these proposals, current management systems for telecommunications networks are constructed on an ad hoc basis. Once system designers have designed a new communications network, or a modification to an existing communications network, the network manager system is created, reflecting the structure, connections and services present in the new network. The conventional management system comprises a management information base, in the form of a data storage device storing electronic data signals describing each of the network elements of the network, their interconnections, and the services and protocols supported by those network elements.
Problems which occur with the conventional approach network management include: